1. Field of the Invention
The technical scope of the present invention is that of the manufacture of metal foams using preforms made with precursors.
2. Description of the Related Art
Metal foam technology is well known and reference may be made to patents EP-1808 241, U.S. Pat. No. 3,236,706 and EP-2118328 which promote manufacturing a preform in the form of granules made from a salt, such as sodium chloride. After the free space between the granules has been filled in with a molten metal, the salt is dissolved to recover the metal foam.
Thus, patent EP-2118328 describes a particularly interesting method that proposes to manufacture a preform with granules made from grain flour. The preform is then baked before the metal is poured in so as to destroy the granule's carbon chains. According to this patent, a paste is first made using flour, sodium chloride and water. This paste is then made into granules, which are then used to manufacture the preform. It was observed that, in addition to the preparation of the paste, this process led to a mechanical fragility of the preform and to a substantial time required for the preform to dissolve prior to the recovery of the metal foam. Lastly, the metal foam incorporates carbonaceous residues after pyrolysis and saline residues which are difficult to remove. Finally, and more seriously, the surface of the metal foam is flawed because of the corrosion and oxidation resulting from the use of sodium chloride which makes its use in industry problematic.